title: Evaluation of the Block Matching deformable registration algorithm in the field of head-and-neck adaptive radiotherapy.
abstract: OBJECTIVE
  To compare the accuracy of the Block Matching deformable registration (DIR) against rigid image registration (RIR) for head-and-neck multi-modal images CT to cone-beam CT (CBCT) registration.
  
  
  METHODS
  Planning-CT and weekly CBCT of 10 patients were used for this study. Several volumes, including medullary canal (MC), thyroid cartilage (TC), hyoid bone (HB) and submandibular gland (SMG) were transposed from CT to CBCT images using either DIR or RIR. Transposed volumes were compared with the manual delineation of these volumes on every CBCT. The parameters of similarity used for analysis were: Dice Similarity Index (DSI), 95%-Hausdorff Distance (95%-HD) and difference of volumes (cc).
  
  
  RESULTS
  With DIR, the major mean difference of volumes was -1.4 cc for MC, revealing limited under-segmentation. DIR limited variability of DSI and 95%-HD. It significantly improved DSI for TC and HB and 95%-HD for all structures but SMG. With DIR, mean 95%-HD (mm) was 3.01 ± 0.80, 5.33 ± 2.51, 4.99 ± 1.69, 3.07 ± 1.31 for MC, TC, HB and SMG, respectively. With RIR, it was 3.92 ± 1.86, 6.94 ± 3.98, 6.44 ± 3.37 and 3.41 ± 2.25, respectively.
  
  
  CONCLUSIONS
  Block Matching is a valid algorithm for deformable multi-modal CT to CBCT registration. Values of 95%-HD are useful for ongoing development of its application to the cumulative dose calculation.
authors.affiliation: Université de Lorraine, CRAN, UMR 7039, 2, Avenue de la forêt de Haye, Vandoeuvre-Les-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, France; Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France. Electronic address: s.huger@nancy.unicancer.fr.
authors.forename: S
authors.initials: S
authors.lastname: Huger
authors.affiliation: Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: P
authors.initials: P
authors.lastname: Graff
authors.affiliation: Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: V
authors.initials: V
authors.lastname: Harter
authors.affiliation: Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: V
authors.initials: V
authors.lastname: Marchesi
authors.affiliation: Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: P
authors.initials: P
authors.lastname: Royer
authors.affiliation: Dosisoft, Avenue Carnot, Cachan 94230, France.
authors.forename: J C
authors.initials: JC
authors.lastname: Diaz
authors.affiliation: Dosisoft, Avenue Carnot, Cachan 94230, France.
authors.forename: S
authors.initials: S
authors.lastname: Aouadi
authors.affiliation: Université de Lorraine, CRAN, UMR 7039, 2, Avenue de la forêt de Haye, Vandoeuvre-Les-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, France.
authors.forename: D
authors.initials: D
authors.lastname: Wolf
authors.affiliation: Université de Lorraine, CRAN, UMR 7039, 2, Avenue de la forêt de Haye, Vandoeuvre-Les-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, France; Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: D
authors.initials: D
authors.lastname: Peiffert
authors.affiliation: Université de Lorraine, CRAN, UMR 7039, 2, Avenue de la forêt de Haye, Vandoeuvre-Les-Nancy Cedex 54506, France; CNRS, CRAN, UMR 7039, France; Institut de Cancérologie de Lorraine Alexis Vautrin, CLCC, Avenue de Bourgogne, Vandoeuvre-Les-Nancy Cedex 54511, France.
authors.forename: A
authors.initials: A
authors.lastname: Noel
mesh_terms: D000465:Algorithms; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D015588:Observer Variation; D011880:Radiotherapy Planning, Computer-Assisted
keywords: CT–CBCT registration; Deformable algorithm; Head and neck cancer